The present invention relates to a diver""s weight belt. More particularly, the present invention relates to a self-adjusting, water pressure-responsive weight belt assembly for use in free diving.
Early sponge divers did not use diving equipment, yet were nevertheless successful in harvesting these primitive marine animals. Of course, sponge diving is still practiced today, and little of the sponge diver""s equipment has changed over time. What the sponge diver""s modicum of equipment gains him in simplicity and convenience is lost in his inability to remain submerged for long periods.
Divers equipped to stay submerged for long periods of time generally fall into two groupsxe2x80x94tethered xe2x80x9chelmetxe2x80x9d divers who rely on remote surface assistance, and free divers who move about free of assistance or support.
Tethered divers most commonly include those with direct links to the surface in the form of safety and air lines, or the xe2x80x9chelmetxe2x80x9d divers. These divers use heavy gear including weighted boots, a pliable suit, and a rigid helmet. This considerable mass is not simply the result of a designer""s quest for durability, but is largely the result of the need to overcome the tendency of humans to float.
Because humans are land dwellers, we have adapted to and are thus able to withstand pressure exerted upon us by air (14 psi or one atmosphere). Once we enter the water, however, the physics of our local environment change significantly, and, for unequipped land dwellers, this environment is hostile. Air has a mass density of 1.29 kg/m3 compared with a mass density of 1.0xc3x97103 kg/m3 at 4xc2x0 C. for water. The diver is subjected to much greater pressure than is, for example, a person strolling upon an adjacent beach. In addition, water pressure is proportional to depth. The deeper the dive, the greater pressurexe2x80x94so great that a pressure of two atmospheres is exerted upon the diver at 10 meters. For every additional 10 meters of depth, the pressure exerted upon the diver increases by one atmosphere.
The laws of physics present humans wanting to dive with a physiological problem. The human body comprises in large part relatively incompressible materials, such as bone (having Young""s Modulus [compression] value of 9.4xc3x97109) and liquids. But the human body is also provided with a series of cavities that normally contain a volume of gases. These cavities include the lungs, the sinuses, the stomach and the inner ear. Each of these cavities is connected with the respiratory system. These cavities not only add to the buoyancy of the diver, but also require that the pressure of the respiratory system be such that these cavities are not allowed to collapse.
Accordingly, the rigid helmeted suit is pressurized from the surface to maintain respiratory pressure, and is also weighted to compensate for the pressurized air. The considerable weight of this diver""s suit is necessaryxe2x80x94such as would be necessary to sink an inflated balloon.
Free divers, those divers who carry their own supply of air in a pressurized cylinder, also have buoyancy problems that must be overcome by weights. In addition to the positive buoyancy created by the diver""s many air-filled body cavities, the diver""s conventional protection against cold waterxe2x80x94the semi-porous wet suitxe2x80x94adds to the overall positive buoyancy.
Beyond their air cylinders, free divers also wear a vest-like device called the xe2x80x9cbuoyancy compensatorxe2x80x9d or the xe2x80x9cb.c.xe2x80x9d that is fluidly connected with the diver""s air supply. The diver can selectively inflate or deflate the b.c. at will as necessary to compensate for pressure changes in the water according to the depth that would otherwise cause the diver to float or sink. To compensate for the air carried in the tank by the diver, the diver""s gas-filled cavities, and the wetsuit, a weight belt is worn, and includes a belt and one or more weights slipped onto the belt through a slotted aperture defined through the weight. The diver traditionally experiments with different amounts of weight that are neither inadequate nor excessive in order to achieve a force to counterbalance his buoyancy.
To insulate himself from the cold of the surrounding water, and as briefly mentioned above, the typical diver utilizes a wet suit comprising a lower part and an upper jacket part (the familiar xe2x80x9cfarmer Johnxe2x80x9d or xe2x80x9cfarmer Janexe2x80x9d suit). A sleeveless and legless xe2x80x9cshortyxe2x80x9d suit is used in warmer waters. The typical wet suit of the diver comprises compressible, semi-porous, expanded neoprene material. And this is where a big part of the diver""s buoyancy problem arises.
The wet suit must be elastic to accommodate the shape of the diver""s body. Neoprene is the material of choice, in that it allows water to flow in and out to xe2x80x9cbreathexe2x80x9d. Neoprene, as noted, is also compressible, and as water pressure increases, so the thickness of the wet suit is reduced by compression. This characteristic in itself is not a problem, but it is a problem with respect to the weight belt, which does not compress. At depth, the diver""s weight belt, which fits snugly on the surface, does not fit properly due to the reduction of the outer dimension of the wet suit, and tends to work its way toward the diver""s legs. With all of the diver""s other underwater concerns, a maladjusted weight belt is an unacceptable inconvenience. This problem becomes more acute during an ascent where gravity exerts a force upon the belt that is exaggerated by the upward motion of the diver.
Weight belt accessories have been designed in the past in an effort at overcoming this problem. For example, U.S. Pat. No. 3,470,570 issued in 1969 to Christiansen discloses an expansible diver""s weight belt that comprises xe2x80x9c[a]n elastic element [having] ends secured to spaced portions of the belt and threads through an accordion-folded portion of the belt.xe2x80x9d While improving the situation somewhat, many divers have found that this construction fails to provide relief because the mass of the weights easily overcome the resistance provided by the elastic elements of Christiansen""s belt accessory. Simply, the problem still exists.
Accordingly, prior approaches to solving the problem of providing a weight belt that truly responds to changes in water pressures brought about by the diver""s passing through waters of different depths have failed.
It is therefore the general object of the present invention to provide a self-adjusting, water pressure-responsive weight belt assembly that overcomes the problems of known weight belts.
A specific object of the present invention is to provide such a belt assembly that responds immediately and directly to changes in water pressure.
An additional object of the present invention is to provide such a belt with a flexible belt portion and a tensioning portion.
A further object of the present invention is to provide such a belt assembly that includes a housing and a reciprocating member, at least a portion of which is reciprocatingly disposed within the housing.
Yet another object of the present invention is to provide such a belt assembly in which a quantity of gas is captured between the interior walls of the housing and the reciprocating member.
Still a further object of the present invention is to provide such a belt assembly in which the reciprocating member may be an interchangeable weight and may thus be interchanged with weights of different values.
An additional object of the present invention is to provide such a belt assembly in which the utilization of a reciprocating member in the form of an interchangeable weight eliminates the need for additional conventional weights to be fitted to the weight belt.
It is a further object of the present invention to provide such a belt assembly having a housing that is composed of a durable yet readily formed polymerized material.
Another object of the present invention is to provide such a belt assembly that is resistant to both salt water and fresh water.
Yet a further object of the present invention is to provide such a belt assembly that is relatively simple to maintain and to operate.
These and other objects are accomplished by the provision of a self-adjusting, water pressure-responsive weight belt assembly for use in free diving in which the tension of the belt is self-adjusting according to changes in ambient water pressure. The weight belt according to the present invention includes a flexible belt portion and a tensioning portion. The tensioning portion effects changes in the overall length of the weight belt assembly in direct response to changes in water pressure. The flexible belt portion includes a conventional weight belt buckle for attachment and release. The tensioning portion is fitted to the flexible belt portion.
The tensioning portion comprises a housing and a reciprocating member that is substantially reciprocatingly disposed within the housing. The housing comprises a substantially hollow base and a housing cover. A first end of the flexible belt portion is attached to the substantially hollow base. The housing cover is releasably attached to the housing base and includes a reciprocating member slot defined therein. The reciprocating member is reciprocatingly movable substantially within the hollow base of the housing. The reciprocating member may be a hollow member or may be a solid weight. An end of the reciprocating member is situated external of the housing by being disposed in a position partially outside of the reciprocating member housing cover through the slot defined therein. The other end of the flexible belt portion is attached to one end of the reciprocating member. One or more O-rings are provided on the portion of the reciprocating member which is disposed within the housing. An air space of variable volume exists within the interior of the water pressure responsive assembly and is defined by the inner walls of the reciprocating member housing base and an end wall of the reciprocating member. The O-rings form a fluid-tight seal which resists entry of water into the air space of the pressure responsive assembly.